This invention is generally directed to new toner compositions and developer compositions, containing certain charge enhancing additives. More specifically, the present invention is directed to developer compositions containing toner particles and negative charge enhancing additives comprised of aryl sulfones, or aryl sulfonamides, which additives impart a negative charge to the toner resin particles. Developer compositions containing the charge enhancing additives of the present invention are useful for causing the development of electrostatic latent images, including color images. Furthermore, the colored developer compositions of the present invention can be selectred for use with common carrier particles comprised of the same composition.
Developer compositions containing charge enhancing additives which impart a positive charge to the toner resin particles are known. However, very few developer compositions have been described in the prior art wherein the charge enhancing additives are selected for the purpose of imparting a negative charge to the toner resin particles. Examples of toner compositions containing charge enhancing additives which impart a positive charge to the toner resin particles include those described in U.S. Pat. No. 3,893,934, wherein there is disclosed the use of certain quaternary ammonium compounds as charge control agents for electrostatic toner compositions; U.S. Pat. No. 4,298,672, which discloses developer compositions containing as charge enhancing additives certain alkyl pyridinium halides, such as cetyl pyridinium chloride; and U.S. Pat. No. 4,338,390, wherein there is illustrated the use of certain sulphates and sulphonates, including stearyl dimethyl phenethyl ammonnium para-toluene sulphonate, as positive charge enhancing additives.
Moreover, there is described in a copending application negative charging enhancing additives comprised of ortho-halophenylcarboxylic acids, and the use of developer compositions containing such additives for causing the development of colored images in xerographic imaging systems.
Nevertheless, there continues to be a need for toner compositions contianing negative charge enhancing additives, that is where a negative charge is imparted to the toner resin particles. Additionally, there is a need for developer compositions containing charge enhancing additives that are capable of imparting substantially similar negative charges to the toner particles irrespective of color. Furthermore, there continues to be a need for toner compositions which can be incorporated into developer compositions containing common carrier particles, which developer compositions can be selected for use in developing colored xerographic images. Moreover, there continues to be a need for toner, and developer compositions, which are humidity insensitive, of uniform charge distribution, and which possess fast charging characteristics.
Also, there continues to be a need for negative charge enhancing materials that are compatible with the toner resin particles, and are relatively non-toxic in comparison to prior art negative charge enhancing additives, such as certain organic acids, fluoro acids, and metal complexes of organic acids, which acids are not completely compatible with the toner resin particles, and in many instances these acids are considered to be toxic.